Versatile interface smart card

ABSTRACT

A smart card that is compatible with multiple different protocols includes a standard set of contacts that comply with the protocols of a published standard, and another contact not designated by the standard which is used to indicate whether the card is to operate in a non-standard mode. When the card is to operate in the non-standard mode, a simple start-up procedure is employed which does not require strict timing constraints, enabling a less expensive interface device to be used. The interface device can be connected to any bus of a computer which operates in accordance with a desired non-standard protocol. Due to the flexibility and functionality offered by smart cards that have microprocessors incorporated therein, the multi-protocol smart card can be used to drive, or otherwise communicate with, any of a variety of peripheral devices, whether or not a personal computer is present in the system.

FIELD OF THE INVENTION

The present invention is directed to microprocessor-based user cards,commonly known as "smart cards", and more particularly to a smart cardthat is capable of communicating with a variety of external devicesusing different protocols that are respectively associated with thevarious devices.

BACKGROUND OF THE INVENTION

The use of secure smart cards that provide information specific to anindividual is becoming more prevalent in a number of different types ofsituations. Examples of such include electronic commerce, securityaccess control and health care record maintenance. Each system whichemploys smart cards contains two fundamental components, namely thesmart cards themselves and an interface device, commonly known as areader. The smart cards are carried by the users of the system, andinclude a memory which stores information that is pertinent to theuser's interaction with the system. In an electronic commerce system,for example, each smart card may contain the balance in an accountmaintained by the user, as well as details of account transactions. Morerecently, the smart cards also include microprocessors, which providefor an increased level of security over the information stored in thecards. The incorporation of microprocessors into the cards also enhancestheir flexibility, for instance by facilitating the storage ofexecutable programs in the cards that can be used to provide expandedfunctionality.

The readers communicate with the cards in a secure manner to access theinformation stored therein. In one type of system, the card is insertedinto a slot in the reader, which brings electrical contacts in thereader into engagement with mating contacts on the exterior of the card.The engaged contacts enable a microcontroller in the reader tocommunicate with the memory and/or microprocessor in the card.Typically, the reader is connected to a peripheral device that isassociated with the particular type of system into which the reader isincorporated. In a security system, for example, the reader might beconnected to an electronic lock that permits a door to be opened. In abanking system, the reader could be incorporated into an automaticteller machine.

To permit the cards and readers of different manufacturers to becompatible with one another, a set of standard specifications has beendeveloped. One of the common standards that applies to smart cards andreaders is ISO 7816, promulgated by the International StandardsOrganization. This standard provides specifications for the location ofthe electrical contacts on the exterior of the cards, as well as thefunctions of the electrical signals that are present at the respectivecontacts. In this regard, the standard provides for up to eightelectrical contacts, although specific signals are defined for only fiveof these contacts. The standard also contains specifications for thepower-up, or initialization, procedure that is carried out when a cardis first inserted into the reader, and the protocol for communicatingbetween the card and the reader.

Due to the need to comply with the published standards, a conventionalcard reader can turn out to be a relatively expensive item of equipment.For instance, the ISO standard requires that different respectivesignals be applied to the five designated contacts on the card in aspecific sequence at predetermined times during the power-up procedure.As a result, the reader must include a controller which supervises theapplication and timing of these signals, thereby adding to its cost.

In many systems which currently employ smart cards, the number of userscan be quite large. For example, in an electronic banking system, aconsiderable number of customers might be expected to access anautomated teller machine each day. Consequently, the cost of the readeris amortized over a sufficient number of transactions that it can bereadily justified by the provider of the services.

More recently, there has been a trend toward personalized types of smartcard applications. For instance, the ability to execute softwareprograms from a microprocessor-based smart card makes it desirable to beable to connect the card to a personal computer. One approach for doingthis is to add a smart card reader to the computer, either as anintegral device or as a peripheral add-on. However, due to theappreciable cost of a reader, personal computer users may not beinclined to adopt this approach. In contrast to large institutions suchas banks and the like, individual computer users may not be able toamortize the cost of the reader over a sufficient number of transactionsto justify its cost.

It is desirable, therefore, to provide a smart card system which doesnot require a relatively expensive reader to access the informationand/or functionality present in a card. With such a capability, thesmart card is able to directly communicate with a variety of differenttypes of peripheral devices that do not require a protocol associatedwith ISO standards and the like. Consistent with this objective,however, it is further desirable to provide such a system which remainscompatible with currently existing smart card systems that comply withestablished standards.

SUMMARY OF THE INVENTION

In accordance with the present invention, these objectives are achievedby providing a smart card that is compatible with multiple differentprotocols. In one embodiment, such a card is fully compatible with theprotocols of the ISO standard and another, non-ISO, standard. One of thecontacts of the card which is not designated by the standard is used toindicate whether the card is to operate in the ISO-standard mode, or inanother mode. When no signal is present at this terminal, the cardoperates in the conventional ISO-standard mode. However, the presence ofa predetermined signal provides an indication that the card is tooperate in the non-ISO mode. In this case, a different start-upprocedure can be employed which does not require the strict timingconstraints associated with the ISO mode of operation. Consequently, aless expensive reader can be employed which may not require the type ofcontroller that is associated with an ISO-compliant reader.

In a specific embodiment, the non-ISO mode can be one that is associatedwith standard communication protocols that are used in personalcomputers, such as PS/2, USB and the like. An interface device whichcommunicates with a multi-protocol smart card can be connected to anybus of the computer which operates in accordance with the desirednon-ISO protocol. In the case of PS/2, for example, the interface devicecan be connected between the keyboard and the CPU of the computersystem. Whenever a smart card is inserted into such an interface device,it communicates with both the CPU and the keyboard in accordance withthe PS/2 protocol.

The applications of the multi-protocol card are not limited tocommunications with personal computers. Due to the flexibility andfunctionality offered by smart cards that have microprocessorsincorporated therein, the multi-protocol smart card can be used todrive, or otherwise communicate with, any of a variety of peripheraldevices, whether or not a personal computer is present in the system.

Further features of the invention, and the advantages offered thereby,are explained in detail hereinafter, with reference to specificembodiments of the invention illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a personal computer system which isconfigured to operate with a smart card;

FIG. 2 is a plan view of a smart card and a reader;

FIG. 3A is a more detailed view of the electronic components of aconventional smart card;

FIG. 3B is a detailed view of the electronic components of a smart cardin accordance with a first embodiment of the present invention;

FIG. 4 is a flowchart of the general mode of operation of the presentinvention;

FIG. 5A is a block diagram of a reader that conforms to the ISOstandard;

FIG. 5B is a schematic diagram of an interface device in accordance withthe present invention;

FIG. 6 is a block diagram of a second embodiment of the presentinvention; and

FIG. 7 is a block diagram of a third embodiment of the presentinvention.

DETAILED DESCRIPTION

To facilitate an understanding of the principles and features of thepresent invention, it is described hereinafter in the context of aspecific embodiment. In particular, reference is made to animplementation of the invention in which a smart card can be connectedto a personal computer. It will be appreciated, however, that thepractical applications of the invention are not limited to thisparticular embodiment. Rather, the invention can be employed in avariety of different systems in which it is desirable to utilize thefunctionality of a smart card without the need for a reader thatstrictly conforms to published standards for smart cards.

FIG. 1 is an illustration of a conventional personal computer systemwhich is configured to operate with a smart card. As is typical, thecomputer system might include a central processing unit (CPU) 10 and thebasic input and output devices that are employed by the user to interactwith programs being executed by the CPU, such as a keyboard 12 and amonitor 14. In addition, the system shown in FIG. 1 includes a smartcard reader 16 as another peripheral device. In a conventionalarrangement, the reader conforms to the ISO standard, and the exchangeof information between a smart card and the reader is carried out inaccordance with a protocol established by that standard. The reader canbe connected to the CPU via a standard input/output port, such as anRS232 serial port. Alternatively, the structure of the reader might beincorporated into the housing for the CPU or the keyboard, which wouldthen include an appropriate slot for insertion of the smart card.

A configuration such as that shown in FIG. 1 might be desirable for avariety of different applications. At a first level, the smart card canbe used to control access to the personal computer. For instance, beforethe user is allowed to run a particular program or open a sensitivefile, he or she may be required to insert his or her personal smart cardinto the reader 16 and enter a password via the keyboard 12. In a knownmanner, the smart card and the reader communicate with one another toauthenticate the password, and thereafter authorize the computer tooperate in the manner commanded by the user. In a more sophisticatedapplication, the smart card might include one or more personalizedsoftware programs which can be executed by the microprocessor in thesmart card and interact with the CPU, such as an electronic bankingprogram.

One of the concerns with a configuration such as that shown in FIG. 1 isthe fact that the security of information pertaining to the smart cardcould be compromised. In particular, when the user enters his or herpassword via the keyboard, that information must pass through thecontrol of the CPU in order to be presented to the smart card. Thiscommunication path is not entirely secure, since it is capable of beingexternally accessed. For instance, the CPU could be programmed tocapture and store the user's password as it is being transmitted to thereader. The stored password could then be retrieved at a later time by aperson who is not the rightful owner of the smart card.

As described previously, another concern is the fact that the readeritself can be relatively expensive, particularly if it is ISO-compliant.Because of the expense, many individual users may not desire to purchasesuch a device, and thereby forego the added functionality that a smartcard would otherwise provide.

In accordance with the present invention, these concerns are alleviatedby providing a smart card that is capable of operating in a mode otherthan that which is defined by the ISO standard. For instance, a smartcard which can operate in accordance with the PS/2 protocol would becapable of communicating directly with the keyboard 12, without theintervention of the CPU, and thereby provide a more secure path for thetransfer of personalized data, such as a password. In addition, whenoperating in such a mode, an ISO-compliant reader would not be required,thereby reducing the cost required to configure the computer to workwith a smart card.

In a preferred embodiment of the invention, the smart card is capable ofselectively operating in both a normal ISO-compliant mode, and at leastone non-ISO mode, to optimize its utility. In this manner, the smartcard can be used with established systems that are commonly associatedwith ISO readers, such as building access control, electronic bankingtransactions, and the like. In addition, it can also be used for other,less frequently employed features, such as to gain access to a protectedpersonal computer.

The basic structure of a smart card system, insofar as it pertains tothe present invention, is illustrated in FIG. 2. Generally speaking, asmart card 18 is a user card made of plastic or other suitable material,similar to a common credit card, and having a number of electricalcontacts 20 on one exterior surface thereof. Embedded within thestructure of the card is an electronic memory 22 and, in a preferredembodiment of the invention, a microprocessor 24. For ease ofillustration, in FIG. 2 the memory 22 and microprocessor 24 are shownoffset from the contacts 20, but in practice they can be locateddirectly beneath the contacts. The dimensions of the card 18, and thearrangement and location of the contacts 20, are determined byapplicable standards. The particular card shown in FIG. 2 has eight suchcontacts, although cards with only six contacts also comply with knownstandards.

The reader 16 has a slot 26 that is appropriately dimensioned to receivethe card 18. The bottom of the slot has a switch 28, or other form ofsensor, to detect when the card is fully inserted into the slot. Theinterior surface of the slot has a set of mating contacts (not shown),which engage corresponding contacts 20 on the card when it is fullyinserted. When the sensor detects that a card is completely insertedinto the slot 26 of the reader, it sends a signal which causes thereader to initiate a power-up procedure, described in detailhereinafter.

An expanded view of the contacts 20 on the smart card, and theirconnection to the internal microprocessor 24 of the card, is illustratedin FIG. 3A. Referring thereto, the ISO standard specifies the particulartype of signal that is associated with five of the eight contacts. Thesesignals include power (Vcc), ground, reset, clock and input/output. Theother three contacts are not assigned to any signal, and therefore arenot used under the ISO protocol. Each of the contacts 20 is connected tothe microprocessor 24 by means of a pull-up resistor 30, so that, in theabsence of a signal at a given contact, the input signal to themicroprocessor 24 is at a logical high level. Hence, the signals at thethree unassigned contacts always remain at the logic high level.

In operation, when a card 18 is inserted into the slot 26 of the reader16, it actuates the sensor 28 when it reaches the end of travel in thedirection of the arrow shown in FIG. 2. Upon receipt of a signal fromthe sensor, a microcontroller (not shown) within the reader applies theappropriate signals to the contacts 20 of the card, in a predeterminedorder specified by the ISO standard. Specifically, the standard requiresthat the ground reference potential be connected first, followed by theVcc power supply voltage. Once the power is connected in this sequence,the clock signal is provided, and then a reset signal is applied.Thereafter, communications between the reader and the internalcomponents 22, 24 of the card 18 are carried out via the I/O contact.

In accordance with the present invention, one or more of the unassignedcontacts is used to expand the functionality of the smart card, byenabling it to operate in accordance with non-ISO protocols. FIG. 3Billustrates a first embodiment of the contact assignment for a smartcard having multi-protocol capabilities. In this embodiment, a sixthcontact 32 functions as a mode indicator. When the card is inserted intoan ISO-compliant reader, no signal is presented to the mode contact.Consequently, the mode input signal to the card's microprocessor 24 isat a logic high level, as in the normal case. The microprocessortherefore operates in accordance with the standard ISO protocol.

The functionality of the mode contact also permits the card to beoperated in accordance with a different type of protocol. In thiscontext, the card is used with an interface device that applies a"non-ISO" mode signal to the mode contact 32. In a card of the typeshown in FIG. 3A, where each of the inputs to the internalmicroprocessor 24 is normally pulled to a logic high level, the non-ISOmode signal would therefore be a logic low signal. As depicted in FIG.3B, the interface device might connect the mode contact 32 directly tothe ground reference potential that is also supplied to the GND contact.Upon detecting a low-level signal at the mode contact 32, themicroprocessor 24 switches its mode of operation, to communicate inaccordance with a predefined protocol other than the standard ISOprotocol.

FIG. 4 illustrates a flow chart which depicts the operation of a smartcard in accordance with the first embodiment of the invention. Referringthereto, when the card is fully inserted into the interface device, themicroprocessor 24 is first powered up, and a reset signal is thenapplied from the interface device. In response to the reset signal, themicroprocessor performs a standard initialization routine, and thenchecks the status of the input signal at the mode contact. If the modesignal is at a logic high level, this indicates that the card has beeninserted in an ISO-compliant reader, and consequently the microprocessor24 communicates via the I/O channel using the standard ISO protocol. If,however, the logic signal at the mode contact has been pulled low, thecard's microprocessor communicates via the I/O channel using a non-ISOprotocol, such as PS/2, USB or I2C, for example.

One advantage that arises from the ability to operate in a non-ISO modeis the fact the that interface device can be significantly simplified.FIG. 5A illustrates a reader that conforms to the ISO standard. Thatstandard requires that each of the respective signals be applied to thefive designated contacts of the card in a predetermined order, and withstrictly controlled timing, during the power-up procedure. To providethe necessary control over the application of the signals, therefore,the reader 16 includes a microcontroller 34 which receives, as inputsignals, the Vcc and ground power signals, as well as a clock signalthat is derived from a crystal oscillator 36, or the like. Dependingupon the particular application, the microcontroller might receive datasignals that are provided from an external source. The microcontroller34 also receives a signal from the sensor 28, which indicates when thecard 18 is fully inserted into the slot 26 in the reader. In response tothis signal, the microcontroller controls the application of therespective signals to each of the five assigned contacts of the card.

In a non-ISO mode of operation, the timing requirements associated withthe power-up procedure are not as rigid, and therefore a moreconventional initialization circuit can be employed. For instance, thereset signal can be generated by a simple RC timing circuit, asillustrated in FIG. 5B. Upon receipt of a signal from the sensor 28, theRC timing circuit is actuated to apply a reset pulse to the appropriatecontact 20 after a period of time that is determined by its timingconstant. Hence, the need for a more expensive microcontroller can beeliminated, thereby reducing the cost of the interface device. Ofcourse, any other suitable type of reset circuit can be employed aswell. To distinguish this simplified interface device from aconventional ISO-compliant reader, it will be referred to herein as anadapter.

Another advantage that stems from the ability to operate in accordancewith different protocols lies in the fact that the card can communicatedirectly with devices that employ non-ISO protocols. This aspect of theinvention is described in greater detail with reference to a secondembodiment, which is schematically illustrated in FIG. 6. For ease ofillustration, the layout of the contacts is rearranged in FIG. 6,relative to that shown in FIGS. 3 and 5. In this particular embodiment,the adapter, and hence the card, is located in the communication pathbetween the CPU 10 and the keyboard 12 of a personal computer system. Ina computer which utilizes the Micro Channel Architecture, for example,communications over the bus between the keyboard and the CPU are carriedout in accordance with the PS/2 protocol. FIG. 6 illustrates the fourbasic signal lines that are present in this bus. These signal linesinclude the two power lines associated with the ground referencepotential and a positive voltage, e.g. 5 volts. The other two linesconstitute an input/output path for data signals, and a path for thedata rate clock.

The adapter for the smart card is connected to the keyboard bus in themanner illustrated in FIG. 6. The two power lines are directly connectedto the corresponding contacts of the adapter. In addition, the clockline of the keyboard bus is connected to one of the three terminals thatare not designated according to the ISO standard. It is to be noted thatthe clock signal which appears on the keyboard bus is different from theclock signal that is applied to the internal microprocessor 24 of thecard. Specifically, the clock which is applied to the microprocessor isone which controls the overall operation associated with themicroprocessor, and is labeled CLK_(M). This clock signal is applied tothe usual clock terminal, by means of an oscillator 36 within theadapter, for example. In contrast, the clock signal CLK_(D) which isobtained from the keyboard bus pertains to the rate at which data istransmitted over the I/O channel of the bus. Since this clock signal isnot defined in the ISO standard, it is applied to one of the unassignedcontact terminals.

A switch 38 is inserted in the I/O channel of the keyboard bus, topermit this channel to be opened whenever a card is inserted in theadapter. To this end, the switch is responsive to the sensor 28 whichdetects that the card is fully inserted into the adapter. In anexemplary embodiment, the switch can be mechanically opened by the carditself. The I/O channel on one side of the switch is connected to thenormal I/O terminal of the smart card, which is labelled I/O₁. Anotherone of the normally unassigned terminals of the card constitutes asecond I/O contact, and is connected to the I/O channel of the bus thatis on the other side of the switch. When no card is inserted in theadapter, data is bidirectionally transmitted between the keyboard andthe CPU over the bus I/O channel, in a normal fashion, with the switchclosed. When a card is inserted into the adapter, the data passesthrough the two I/O terminals on the card. The smart card can operate ina passive mode or an active mode. In a passive mode, the data is simplytransferred between the two I/O terminals, without disturbance. In anactive mode, the microprocessor 24 in the card can receive datatransmitted by either the CPU or the keyboard, and likewise can transmitdata to either or both of these devices.

The direct connection between the smart card and each of the CPU and thekeyboard provides a secure channel for the transfer of sensitive data.For example, in a situation where the user enters his or her passwordvia the keyboard, that data is transmitted directly to the smart card,without going to the CPU. Once the proper password has been entered, thefunctionality provided by the smart card can then be employed inconnection with the personal computer. For example, electronic bankingtransactions can be carried out in connection with account informationthat is securely stored in the smart card.

From the foregoing, it will be appreciated that the ability to operatethe smart card in accordance with different protocols permits the smartcard to be used in connection with a variety of different types ofperipheral devices. While the embodiment of FIG. 6 comprises a systemthat includes a personal computer with a keyboard, it is not necessarythat an external CPU be present. Rather, the smart card could be usedwith standalone devices, such as a PIN pad for entering passwords, adisplay device, or a modem. The only requirement is that the peripheraldevice include an I/O channel and a data clock which can be accessed bythe smart card, as in the embodiment of FIG. 6. As an example, FIG. 7illustrates an embodiment in which the smart card is used to control aterminal which essentially comprises a keyboard and a display. All ofthe functionality that is needed to operate the terminal is containedwithin the smart card itself. One I/O contact of the smart card is usedfor bidirectional communications with the keyboard, and the other I/Ocontact functions to drive the display. A particular advantage of thisarrangement resides in the fact that executable programs, such asapplets written in the JAVA programming language, can be downloaded intothe smart card, and then used to control the terminal to provide avariety of different functions. Since the JAVA programming language isnot platform specific, the terminal need not be uniquely associated witha given card. Rather, terminals from a variety of differentmanufacturers can be operated with the same card.

This type of operation provides additional security as well. Since allof the operations of the terminal are managed by the card itself, thereis no need to provide any form of intelligence within the terminalitself, or to store any secure type of information therein. Furthermore,while the multi-protocol card offers this expanded range offunctionality, it still remains compatible with the ISO standard, andtherefore can be used for conventional smart card applications.

It will be appreciated by those of ordinary skill in the art that thepresent invention can be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Forexample, while the disclosed embodiments depict a card which canselectively operate in accordance with two protocols, it is possible toemploy a greater number of protocols for a greater flexibility. Forinstance, the mode contact 32 can indicate whether the card is tooperate pursuant to the ISO protocol or a non-ISO protocol. If a non-ISOprotocol is to be used, data provided over one of the I/O channels canidentify any one of a plurality of different protocols to be used withthe adapter in the non-ISO mode.

The presently disclosed embodiments are therefore considered in allrespects to be illustrative, and not restrictive. The scope of theinvention is indicated by the appended claims, rather than the foregoingdescription, and all changes that come within the meaning and range ofequivalence thereof are intended to be embraced therein.

What is claimed is:
 1. A multi-protocol smart card system, comprising:auser card containing a microprocessor and associated memory, and aplurality of contacts for transferring data to and from saidmicroprocessor and memory, said contacts including a first set ofcontacts respectively associated with a set of signals that conform to afirst protocol, and at least one other contact for controlling saidmicroprocessor to operate in accordance with a second protocol; and aninterface device for receiving said user card, and having:a first set ofmating contacts which correspond to the first set of contacts in saiduser card, to transfer said signals that conform to said first protocol,a mode contact that corresponds to said other contact of the user card,and a mode signal generator that provides a signal at said mode contactwhich causes said microprocessor to operate in accordance with saidsecond protocol mode when the user card is received in said interfacedevice.
 2. The smart card system of claim 1, wherein said first protocolis an ISO protocol that pertains to smart cards, and said secondprotocol is a non-ISO protocol.
 3. The smart card system of claim 2wherein said non-ISO protocol is selected from the group comprisingPS/2, USB and I2C protocols.
 4. The smart card system of claim 1,wherein said microprocessor selectively operates in accordance with aplurality of non-ISO protocols in accordance with a signal provided bysaid mode signal generator.
 5. The smart card system of claim 1, whereinsaid other contact of the user card is not used when said microprocessoroperates in accordance with said first protocol.
 6. The smart cardsystem of claim 5, wherein said other contact is normally maintained ata predetermined logic level during operation in accordance with saidfirst protocol, and said mode signal generator switches said othercontact to a different logic level when the microprocessor is to operatein accordance with said second mode.
 7. The smart card system of claim 6wherein said different logic level is a ground reference potential. 8.The smart card system of claim 1 wherein said interface device furtherincludes a reset signal generator for applying a reset signal to one ofthe contacts of the user card.
 9. The smart card system of claim 8wherein said reset signal is applied to one of the contacts of saidfirst set of contacts.
 10. The smart card system of claim 8 wherein saidreset signal generator comprises an RC timing circuit.
 11. In atransaction system of the type in which a user card having amicroprocessor communicates with an interface device to perform atransaction, a method for selectively operating said microprocessor inone of a plurality of modes, comprising the steps of:placing a user cardin an operative relationship with an interface device so as to permitsignals to be exchanged between the user card and the interface device;providing signals to the user card from the interface device by means ofa predefined set of communication contacts associated with a firstoperating protocol; selectively providing a mode signal to the user cardfrom the interface device in accordance with a mode of operationassociated with the interface device; determining within themicroprocessor of the user card whether the mode signal is beingprovided by the interface device; and operating said microprocessor inaccordance with said first operating protocol when said mode signal isnot being provided, and operating said microprocessor in accordance witha second operating protocol different from said first protocol when saidmode signal is being provided.
 12. The method of claim 11 wherein saidmode signal is provided to the user card by means of a communicationcontact other than the contacts of said predefined set of contacts. 13.The method of claim 11, wherein said first protocol is an ISO protocolthat pertains to smart cards, and said second protocol is a non-ISOprotocol.
 14. The method of claim 13, wherein said non-ISO protocol isselected from the group comprising PS/2, USB and I2C protocols.
 15. Auser card for a multi-protocol smart card system, comprising:a user cardcontaining a microprocessor that is capable of selectively operating inaccordance with a plurality of different operating protocols; a firstset of contacts on said user card for communicating signals to and fromsaid microprocessor in accordance with a first one of said operatingprotocols; at least one other contact on said user card for providing amode signal to said microprocessor; and means associated with saidmicroprocessor for determining whether a mode signal is provided to saidother contact, and for causing said microprocessor to operate inaccordance with said first protocol when a mode signal is not provided,and thereby communicate signals using only said first set of contacts,and to cause said microprocessor to operate in accordance with a second,different protocol when said mode signal is provided.
 16. The user cardof claim 15, wherein said first protocol is an ISO protocol thatpertains to smart cards, and said second protocol is a non-ISO protocol.17. The user card of claim 16 wherein said non-ISO protocol is selectedfrom the group comprising PS/2, USB and I2C protocols.
 18. An interfacedevice for use in connection with a multi-protocol user card,comprising:a first set of mating contacts which correspond to a firstset of contacts in said user card that are respectively associated witha set of signals that conform to a first protocol, to transfer saidsignals that conform to said first protocol, a mode contact thatcorresponds to another contact of the user card, and a mode signalgenerator that provides a signal at said mode contact which causes amicroprocessor in a user card to operate in accordance with a secondprotocol mode when the user card is received in said interface device.19. The interface device of claim 18, wherein said first protocol is anISO protocol that pertains to smart cards, and said second protocol is anon-ISO protocol.
 20. The interface device of claim 19, wherein saidnon-ISO protocol is selected from the group comprising PS/2, USB and I2Cprotocols.
 21. The interface device of claim 18, wherein said modecontact is normally maintained at a predetermined logic level duringoperation in accordance with said first protocol, and said mode signalgenerator switches said other contact to a different logic level whenthe microprocessor is to operate in accordance with said second mode.22. The interface device of claim 21 wherein said different logic levelis a ground reference potential.
 23. The interface device of claim 18wherein said interface device further includes a reset signal generatorfor applying a reset signal to one of the contacts of the user card. 24.The interface device of claim 23 wherein said reset signal is applied toone of the contacts of said first set of contacts.
 25. The interfacedevice of claim 23 wherein said reset signal generator comprises an RCtiming circuit.
 26. In a transaction system of the type in which a usercard having a microprocessor communicates with an interface device toperform a transaction, a method for selectively operating saidmicroprocessor in one of a plurality of different protocols forcommunication between the card and the interface device, comprising thesteps of:placing a user card in an operative relationship with aninterface device so as to permit signals to be exchanged between theuser card and the interface device; providing signals to the user cardfrom the interface device by means of a predefined set of communicationcontacts associated with a first communication protocol; providing amode signal to the user card from the interface device that isassociated with a second communication protocol; detecting within themicroprocessor of the user card whether the mode signal is beingprovided by the interface device; and operating said microprocessor inaccordance with said first communication protocol when said mode signalis not detected, and operating said microprocessor in accordance withsecond communication protocol when said mode signal is detected.
 27. Themethod of claim 26 wherein said mode signal is provided to the user cardby means of a communication contact other than the contacts of saidpredefined set of contacts.
 28. The method of claim 26, wherein saidfirst protocol is an ISO protocol that pertains to smart cards, and saidsecond protocol is a USB protocol.
 29. A user card for a multi-protocolsmart card system, comprising:a user card containing a microprocessorthat is capable of selectively operating in accordance with a pluralityof different communication protocols; a first set of contacts on saiduser card for communicating signals to and from said microprocessor inaccordance with a first one of said communication protocols; at leastone other contact on said user card for receiving a signal that is notassociated with said first communication protocol; and means associatedwith said microprocessor for determining whether said signal is presentat said other contact, and for causing said microprocessor to operate inaccordance with said first protocol when said signal is not present, andto cause said microprocessor to operate in accordance with a second,different protocol when said signal is present.
 30. The user card ofclaim 29, wherein said first protocol is an ISO protocol that pertainsto smart cards, and said second protocol is a USB protocol.
 31. The usercard of claim 29 wherein said microprocessor communicates signals usingonly said first set of contacts when operating in accordance with saidfirst protocol.